1 files changed, 107 insertions, 0 deletions
diff --git a/src/saveload/saveload_filter.h b/src/saveload/saveload_filter.h
new file mode 100644
index 000000000..0cb5c8695
--- /dev/null
+++ b/src/saveload/saveload_filter.h
@@ -0,0 +1,107 @@
+/* $Id$ */
+
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file saveload_filter.h Declaration of filters used for saving and loading savegames. */
+
+#ifndef SAVELOAD_FILTER_H
+#define SAVELOAD_FILTER_H
+
+/** Interface for filtering a savegame till it is loaded. */
+struct LoadFilter {
+	/** Chained to the (savegame) filters. */
+	LoadFilter *chain;
+
+	/**
+	 * Initialise this filter.
+	 * @param chain The next filter in this chain.
+	 */
+	LoadFilter(LoadFilter *chain) : chain(chain)
+	{
+	}
+
+	/** Make sure the writers are properly closed. */
+	virtual ~LoadFilter()
+	{
+		delete this->chain;
+	}
+
+	/**
+	 * Read a given number of bytes from the savegame.
+	 * @param buf The bytes to read.
+	 * @param len The number of bytes to read.
+	 * @return The number of actually read bytes.
+	 */
+	virtual size_t Read(byte *buf, size_t len) = 0;
+
+	/**
+	 * Reset this filter to read from the beginning of the file.
+	 */
+	virtual void Reset()
+	{
+		this->chain->Reset();
+	}
+};
+
+/**
+ * Instantiator for a load filter.
+ * @param chain The next filter in this chain.
+ * @tparam T    The type of load filter to create.
+ */
+template <typename T> LoadFilter *CreateLoadFilter(LoadFilter *chain)
+{
+	return new T(chain);
+}
+
+/** Interface for filtering a savegame till it is written. */
+struct SaveFilter {
+	/** Chained to the (savegame) filters. */
+	SaveFilter *chain;
+
+	/**
+	 * Initialise this filter.
+	 * @param chain The next filter in this chain.
+	 */
+	SaveFilter(SaveFilter *chain) : chain(chain)
+	{
+	}
+
+	/** Make sure the writers are properly closed. */
+	virtual ~SaveFilter()
+	{
+		delete this->chain;
+	}
+
+	/**
+	 * Write a given number of bytes into the savegame.
+	 * @param buf The bytes to write.
+	 * @param len The number of bytes to write.
+	 */
+	virtual void Write(byte *buf, size_t len) = 0;
+
+	/**
+	 * Prepare everything to finish writing the savegame.
+	 */
+	virtual void Finish()
+	{
+		if (this->chain != NULL) this->chain->Finish();
+	}
+};
+
+/**
+ * Instantiator for a save filter.
+ * @param chain             The next filter in this chain.
+ * @param compression_level The requested level of compression.
+ * @tparam T                The type of save filter to create.
+ */
+template <typename T> SaveFilter *CreateSaveFilter(SaveFilter *chain, byte compression_level)
+{
+	return new T(chain, compression_level);
+}
+
+#endif /* SAVELOAD_FILTER_H */